JP3062069B2 - Electromagnetic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated electromagnetic sensor in which a sensitive element is insert-molded.

[0002]

2. Description of the Related Art There is known an electromagnetic sensor in which a fixed portion to a vehicle body and a covering portion of a sensitive element portion are integrally formed by insert-molding a sensitive element portion including a coil, a pole piece, a permanent magnet, and a yoke. (Japanese Unexamined Patent Publication No.
No. 342002).

[0003] In such an electromagnetic sensor, a primary manufactured sensitive element portion is inserted into a mold, and molten resin is injected into a cavity formed between the inner surface of the mold and the outer surface of the sensitive element portion. By doing so, the whole is integrally configured. Therefore, when forming the covering around the sensitive element section, the sensitive element section must be stably fixed in the mold.

On the other hand, when the above-described electromagnetic sensor is used for a rotational speed detector, it is necessary to cut the tip of the pole piece in accordance with the tooth shape of the pulsar gear in order to increase the magnetic efficiency.

[0005]

However, if the tip of the pole piece is cut, the strength is reduced. Therefore, it is desirable to protect the pole piece by resin molding until the tip is fully filled. However, it is difficult to hold the pole piece at the center of the mold when trying to mold to the tip.

The present invention solves such problems imposed on the prior art, and allows the molten resin to flow into the tip of the pole piece while securely holding the pole piece at the center of the mold. The present invention has been devised for the purpose of providing an electromagnetic sensor provided with the positioning means for the die configured as described above.

[0007]

According to the present invention, a bobbin (7) around which a coil (9) is wound and a pole piece inserted through the center of the bobbin are provided. The sensitive element part (2) having (10) is inserted into a mold (19).
In the electromagnetic sensor (1), a molten resin is injected by inserting into the inside of (20) to form a covering portion (housing portion 3) around the sensitive element portion.
The bottom of the bobbin receiving portion of the mold (lower die 19) is to receive only the protruding portion of the pole piece from the bobbin with a gap.
A recess (23) provided, and by providing a plurality of axially extending portions which generally may closely circumferentially inner surface of the recess (22) in the bobbin, the position of the pole piece with respect to the radial direction of the recess
In addition to making the determination , the molten resin flows around the tip of the pole piece via the gap (G2) between the extending portions adjacent to each other, so that the tip of the pole piece (10
It was configured such that the periphery of a) was molded.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an electromagnetic sensor constructed according to the present invention. In the electromagnetic sensor 1, a housing part 3 covering the periphery of a sensitive element part 2, which will be described later, a mounting stay part 4 for a vehicle body, and a cable lead-out part 5 are integrally formed of a synthetic resin material. The mounting stay 4
, A metal collar 6 for receiving a bolt tightening force is inserted.

The sensitive element section 2 is manufactured in a separate process. As shown in FIG. 2, each of the sensitive element portions 2 has a bobbin 7 formed by injection molding of a synthetic resin material and a pair of terminal members 8 press-fitted and fixed to one end surface of the bobbin 7 in the axial direction. And a coil 9 composed of a conductive wire wound around the bobbin 7 with a pole piece 10, a permanent magnet 11, and a yoke 12 mounted in the center hole of the bobbin 7, and connectors (FIG. (Not shown).

As shown in FIG. 3, the terminal of the conductor 14 of the coil 9 is electrically connected to the conductor holding portion 15 of the terminal member 8 where the terminal is entangled. The layer is melted by heat, and the copper layer of the conductor 14 and the tin layer plated on the terminal member 8 are melted and fused to the conductor holding part 15.

The lead 13 is made to melt by melting the copper layer of the lead 13 and the tin layer plated on the terminal member 8 by applying an electric current to the lead holding portion 16 of the terminal member 8 while crimping the electrode. And the solder previously applied to the end of the lead wire 13 melts into the entire joint,
It is firmly joined to the lead wire holding part 16. Note that high-temperature solder is used as the solder.

Each lead wire 13 is lightly press-fitted into a holding groove 17 formed on one end surface of the bobbin 7, thereby preventing the lead wire 13 from being displaced. Note that a cable retainer 18 is molded in advance on the covering of the lead wire 13.

The tip 10 of the pole piece 10
a is cut corresponding to the tooth profile of the pulsar gear. In order to mold the cut end portion 10a also with resin, a plurality of (about 2 to 4 places, in this embodiment, two or four places, at the lower end of the bobbin 7 that are equally divided around the circumference in contact with the outer peripheral surface of the pole piece 10). And 4) axially extending portions 22
Is formed, and the protrusion of the pole piece 10 from the bobbin 7 is
The outer peripheral surface of the axially extending portion 22 is brought into close contact with the inner peripheral surface of the corresponding recess 23 formed in the lower mold 19 so as to receive only the air gap (see FIG. 4). At the same time, the lower surface of the flange 25 of the bobbin 7 is in contact with the plurality of protrusions 24 protruding from the bottom surface of the bobbin receiving portion of the lower mold 19. Thus, the positioning of the sensitive element portion 2 in the lower mold 19 is ensured.

On the other hand, on the upper end surface of the bobbin 7, three sharp protrusions 26 having sharp tips are projected at equal intervals in the circumferential direction. Correspondingly, three positioning projections 28 are formed on the inner surface of the upper mold 20 so as to have tapered holes 27 that can receive the pointed projections 26 in a complementary manner. Thus, when the mold is closed, the three pointed projections 26 on the upper end surface of the bobbin 7 are fitted into the tapered holes 27 while being guided by the slopes of the tapered holes 27, and the sensitivity in the molds 19 and 20 is increased. The misalignment of the element 2 is corrected, and the sensitive element 2 is
It is securely fixed in the inside 20. Here, the pedestal 2 of the pointed projection 26
9 is formed with a flat surface, and after the pointed protrusion 26 is fitted into the tapered hole 27, the lower surface of the positioning protrusion 28 presses the upper surface of the pedestal 29 so that positioning in the axial direction is performed. It has become. Therefore, no pressing force acts on the tip of the pointed projection 26 with the upper mold 20 closed.

In this manner, the sensitive element portion 2 and the metal collar 6 are set in the lower die 19, the upper die 20 is closed, and the cavity formed between the outer surface of the sensitive element portion 2 and the inner surface of the lower die 19. By injecting the molten resin from the gate 21 to
As shown in FIG. 5, the sensitive element 2 and the collar 6
The housing part 3 and the stay part 4 are
Are integrally formed.

Here, the resin injection gate 21 is provided on the upper mold 20 so as to be located on the center line of the sensitive element section 2. Therefore, the molten resin injected from the gate 21 flows uniformly in all directions on the outer periphery of the sensitive element section 2 and finally covers the entire periphery of the sensitive element section 2. At this time,
The molten resin is filled in a gap G1 between the lower surface of the flange 25 of the bobbin 7 formed by the plurality of protrusions 24 and the lower surface of the lower mold 19.
Then, the air flows into the periphery of the distal end portion 10a of the pole piece 10 through the gap G2 between the plurality of extending portions 22, and the periphery of the distal end portion 10a of the pole piece 10 is also resin-molded.

The dies 19 and 20 in FIG. 2 show only cut end faces. The section of the recess 23 for receiving the pole piece 10 has a cross section along the line II-II in FIG.

[0019]

As described above, according to the present invention, since the center position of the pole piece is securely held in the mold and the molten resin easily flows into the tip portion, the tip portion of the pole piece is cut. Even at this point, it is possible to mold the entire tip. Therefore, the protection effect of the tip of the pole piece is enhanced,
In addition, the pole piece can be prevented from rotating.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electromagnetic sensor according to the present invention.

FIG. 2 is a longitudinal sectional view showing a state where a sensitive element portion and a collar are set in a mold.

FIG. 3 is a perspective view of a main part of a sensitive element unit.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a longitudinal sectional view showing a state in which a sensitive element portion and a collar are molded in a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic sensor 2 Sensitive element part 3 Housing part 4 Mounting stay part 5 Cable lead-out part 6 Metal collar 7 Bobbin 8 Terminal member 9 Coil 10 Pole piece 11 Permanent magnet 12 Yoke 13 Lead wire 14 Lead wire 15 Lead wire holding part 16 Lead wire holding Part 17 Holding groove 18 Cable retainer 19 Lower die 20 Upper die 21 Resin injection gate 22 Axial extension part 23 Concave part 24 Projection part 25 Flange 26 Pointed part 27 Tapered hole 28 Positioning projection 29 Base

Claims (1)

(57) [Claims] 1. A sensitive element part having a bobbin around which a coil is wound and a pole piece inserted through the center of the bobbin is inserted into a mold, and molten resin is injected to form a sensitive element part. An electromagnetic sensor having a coating portion formed therearound, wherein a recess is formed in a bottom surface of a bobbin receiving portion of a mold so as to receive only a protruding portion of the pole piece from the bobbin with a gap.
By providing a plurality of axially extending portions on the bobbin that can be substantially in close contact with the circumferential inner surface of the recess,
Positioning of the pole piece in the radial direction of the recess
And the molten resin flows around the tip of the pole piece through the gap between the extending portions adjacent to each other, so that the periphery of the tip of the pole piece is molded. An electromagnetic sensor, comprising: